Patterns and origin of igneous activity around the Tanzanian craton

Foley, Stephen F.; Link, Klemens; Tiberindwa, J.V.; Barifaijo, E.

doi:10.1016/j.jafrearsci.2011.10.001

Cited by 63 publications

(50 citation statements)

References 130 publications

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“…The best example for lithospheric control on distribution of plume-generated melts is documented in the Tanzanian Craton, which is due to the Afar plume. The majority of magmas occurred along the east-Africa rift system that bounded the craton, but almost no magmatism occurred within the craton (Foley et al, 2012). Such a distribution pattern suggests that the lateral movement of the ascending plume and channeled plume flow along the weak zones that surround the craton (Sleep, 1997).…”

Section: Evidence For Lithospheric Involvementmentioning

confidence: 99%

The Early Permian Tarim Large Igneous Province: Main characteristics and a plume incubation model

Wei

Luo

et al. 2014

Lithos

244

160

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Section: Evidence For Lithospheric Involvementmentioning

confidence: 99%

The Early Permian Tarim Large Igneous Province: Main characteristics and a plume incubation model

Wei

Luo

et al. 2014

Lithos

244

160

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“…Black lines mark segments of the major faults related to the eastern and western branches of the EARS and the connecting Aswa transform fault (after Milesi et al [2004]). The outline of the Tanzania craton is given in red color according to Foley et al [2012]. Yellow spots depict volcanic fields along the northern part of the western branch (T: Toro‐Ankole, V: Virunga, S‐K: South Kivu).…”

Section: The Tanzania Craton and The Earsmentioning

confidence: 99%

“…According to experimentally derived soldidus and liquidus temperatures of peridotite at upper mantle pressures a massive crystallization of mantle melt can be presumed as soon the melt migrates to depth shallower than 100–80 km (melt curve summarized in Foley [2008]). Corresponding to the mineralogy of the xenoliths i.e., phlogopite and the absence of amphibole as well as the very potassic chemistry of the associated volcanoes the source region of the volcanoes that is often regarded as the LAB and that hosts the veins must be at least 100 km deep from a petrological point of view [ Link et al , 2010; Foley et al , 2012]. The very high abundance of clinopyroxene‐phlogopite‐xenoliths and the lack of peridotite xenoliths in the Toro‐Ankole volcanic province are thought to have very intensely infiltrated the lithosphere resulting in massive bodies within the mantle.…”

Section: Shear Wave Velocities From Mineralogymentioning

confidence: 99%

Melt infiltration of the lower lithosphere beneath the Tanzania craton and the Albertine rift inferred from S receiver functions

Wölbern

Rümpker

Link

et al. 2012

Geochem Geophys Geosyst

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[1] The transition between the lithosphere and the asthenosphere is subject to numerous contemporary studies as its nature is still poorly understood. The thickest lithosphere is associated with old cratons and platforms and it has been shown that seismic investigations may fail to image the lithosphere-asthenosphere boundary in these areas. Instead, several recent studies have proposed a mid-lithospheric discontinuity of unknown origin existing under several cratons. In this study we investigate the Tanzania craton in East Africa which is enclosed by the eastern and western branches of the East African Rift System. We present evidence from S receiver functions for two consecutive discontinuities at depths of 50-100 km and 140-200 km, which correspond to significant S wave velocity reductions under the Tanzania craton and the Albert and Edward rift segments. By comparison with synthetic waveforms we show that the lower discontinuity coincides with the LAB exhibiting velocity reductions of 6-9%. The shallower interface reveals a velocity drop that varies from 12% beneath the craton to 24% below the Albert-Edward rift. It is interpreted as an infiltration front marking the upper boundary of altered lithosphere due to ascending asthenospheric melts. This is corroborated by computing S velocity variations based on xenolith samples which exhibit a dense system of crystallized veins acting as pathways of the infiltrating melt. Mineral assemblages in these veins are rich in phlogopite and pyroxenite which can explain the reduced shear wave velocities. Melt infiltration represents a suitable mechanism to form a mid-lithospheric discontinuity within cratonic lithosphere that is underlain by anomalously hot mantle.

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“…Alkaline and highly alkaline intraplate lavas range in composition from slightly undersaturated alkali basalts to strongly undersaturated olivine nephelinites and olivine melilitites (Foley et al 2012;Green and Ringwood 1967). Experimental partial melting of carbonated mantle peridotite reproduced the composition of MgO-rich nephelinite (>12 wt % MgO) but failed to reproduce Mg-poor nephelinite composition, suggesting that MgO-poor magmas are not primary magmas (e.g.…”

Section: Fractional Crystallization From Melilititementioning

confidence: 99%

Nephelinite lavas at early stage of rift initiation (Hanang volcano, North Tanzanian Divergence)

Baudouin

Parat

Denis

et al. 2016

Contrib Mineral Petrol

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International audienceNorth Tanzanian Divergence is the first stage of continental break-up of East African Rift (<6 Ma) and is one of the most concentrated areas of carbonatite magmatism on Earth, with singular Oldoinyo Lengai and Kerimasi volcanoes. Hanang volcano is the southernmost volcano in the North Tanzanian Divergence and the earliest stage of rift initiation. Hanang volcano erupted silica-undersaturated alkaline lavas with zoned clinopyroxene, nepheline, andradite-schorlomite, titanite, apatite, and pyrrhotite. Lavas are low MgO-nephelinite with low Mg# and high silica content (Mg# = 22.4–35.2, SiO2 = 44.2–46.7 wt%, respectively), high incompatible element concentrations (e.g. REE, Ba, Sr) and display Nb–Ta fractionation (Nb/Ta = 36–61). Major elements of whole rock are consistent with magmatic differentiation by fractional crystallization from a parental melt with melilititic composition. Although fractional crystallization occurred at 9–12 km and can be considered as an important process leading to nephelinite magma, the complex zonation of cpx (e.g. abrupt change of Mg#, Nb/Ta, and H2O) and trace element patterns of nephelinites recorded magmatic differentiation involving open system with carbonate–silicate immiscibility and primary melilititic melt replenishment. The low water content of clinopyroxene (3–25 ppm wt. H2O) indicates that at least 0.3 wt% H2O was present at depth during carbonate-rich nephelinite crystallization at 340–640 MPa and 1050–1100 °C. Mg-poor nephelinites from Hanang represent an early stage of the evolution path towards carbonatitic magmatism as observed in Oldoinyo Lengai. Paragenesis and geochemistry of Hanang nephelinites require the presence of CO2-rich melilititic liquid in the southern part of North Tanzanian Divergence and carbonate-rich melt percolations after deep partial melting of CO2-rich oxidized mantle source

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Patterns and origin of igneous activity around the Tanzanian craton

Cited by 63 publications

References 130 publications

The Early Permian Tarim Large Igneous Province: Main characteristics and a plume incubation model

The Early Permian Tarim Large Igneous Province: Main characteristics and a plume incubation model

Melt infiltration of the lower lithosphere beneath the Tanzania craton and the Albertine rift inferred from S receiver functions

Nephelinite lavas at early stage of rift initiation (Hanang volcano, North Tanzanian Divergence)

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